Dual completion packer tool



March 13, 1962 L.. L. GAGE DUAL. COMPLETION PACKER TOOL Filed Nov. 15,1957 INVENTOR.

Lonnie L. Gag- EYQMW@ A TTORN lin- .n m Il Maw , Y A 4 V 3,024,845Patented Mar. 13, 1962 ffice 3,024,846 DUAL COMPLETION PACKER TQQLLonnie L. Gage, i707 Birch St., Duncan, Okla. Filed Nov. l5, 1957, Ser.No. 696,652 5 Claims. (Cl. 166226) This invention relates toimprovements in packers for producing oil wells, and more particularly,but'not by way of limitation, to a dual packer apparatus for permittingdual or multiple completion of oil wells in order to produce well fluidfrom two or more fluid bearing formations.

Many oil well bores extend downwardly into the earth through more thanone oil or gas bearing subsurface formation. It will be apparent that itis very desirable for purposes of economy to produce uid from all of thefluid bearing formations through one well bore in lieu of drillingadditional well bores into each of the oil or gas bearing subsurfaceformations. However, due to governmental regulations, the several oilbearing formations must be produced separately, and may not be allowedto flow simultaneously. At the present time it is Very diflicult toobtain separate oil production from the multiple subsurface formations,and particularly when the fluid bearing sands are disposed atsubstantially great depths in the well bore, such as in excess of fourthousand feet below the surface of the ground.

The most common method today for producing7 fluid from two or more oilbearing sands is to place a packer between the tubing and well casingwithin the well bore, and disposed between the producing sands. One ofthe oil sands may then be produced through the annular space between thewell tubing and well casing, whereas the other oil sand may be producedthrough the well tubing itself. One disadvantage of this type of dualcompletion for oil wells is that paralin tends to accumulate on theinner walls of the well casing. It is very dillicult to remove theparaffin from the walls of the casing, and the accumulation of theparaflin not only interferes with the flow of the well fluid, but alsogreatly hinders the removal of the packer from the well bore when it isnecessary to service the well for any reason.

The present invention contemplates a novel dual completion packerapparatus which provides for producing from multiple oil or gas sandsentirely through the tubing, thereby eliminating any possibility ofparaffin accumulation within the casing. Paran which may adhere to theinner walls of the tubing may be readily removed in any well knownmanner, such as by introducing a hot fluid into the tubing for meltingthe paraflin. This method for remoyal of paraffin is not practical forutilization in well casing.

The novel packer joint is adapted to be interposed within the welltubing string at substantially any desired depth within the well bore inorder to produce fluid from multiple subsurface formations separately,regardless of the depth of the oil bearing formation. The novel toolcomprises a pair of telescopically disposed tubular members whichfunction in the manner of a slide valve for alternately producing fluidfrom the multiple subsurface oil sands. For example, in the event twovertically spaced oil bearing sands are present within the well bore,the novel packer joint may be interposed in the tubing string wherebyone position of the tubular members will provide communication betweenthe upper oil sand and the interior of the well tubing. Simultaneously,the lower oil sand is sealed or packed off whereby the uid containedtherein cannot enter the well tubing. The Huid from the upper sand maythus be produced from the well as desired. When it becomes desirable tocease the flow of fluid from the upper oil sand, and begin theproduction from the lower o-il sand, thepacker tool may be positionedwhereby communication is established between the lower sand and theinterior of the tubing, while the upper sand is simultaneously sealed orpacked off in order to stop the ow or production of the fluid thereinto.The fluid from the lower sand may then be produced from the well in anywell known manner. The tubular members may be readily telescopicallyraised and lowered with respect to each other by raising or lowering thewell tubing at the surface of the well in any well known manner.

It is an important object of this invention to provide a packer jointunit for permitting the dual completion of an oil well whereby multipleoil sands may be produced independently of each other from one wellbore.

It is another object of this invention to provide a dual completionpacker joint whereby a plurality of vertically spaced oil sands may beproduced through the well tubing.

Another object of this invention is -to provide a dual completion packerjoint for oil wells wherein a plurality of vertically spaced oil sandmay be produced independently from each other through a single wellbore.

A further object of this invention is to provide a novel packer jointfor an oil well tubing string which may be easily positioned from thesurface of the well for selectively producing well uid from a pluralityof subsurface oil bearing formations.

It is a still further object of this invention to provide a packer jointfor an oil well tubing string for a dual cornpletion of the Well wherebymultiple oil bearing sands may be produced in a manner wherein theaccumulation of parat-lin on the inner Walls of the well casing issubstantially eliminated.

A still further object of this invention is to provide a dual completionpacker joint for an oil well tubing string which is simple and efhcientin operation :and economical and durable in construction.

Other objects and advantages of the invention will be evident from thefollowing detailed description, read in conjunction with theaccompanying drawings, which illustrate my invention.

In the drawings:

FIGURE 1 is a broken vertical sectional view of the upper portion of thenovel packer joint in a position providing for production from one oilbearing formation.

FIGURE 1A is a vertical sectional View depicting the lower portion ofthe tool shown in FIG. l.

FGURE 2 is a view similar to FIG. l with the novel tool in a positionfor providing for flow of fluid from a second oil bearing formation.

FIGURE 2A is a view similar to FIG. 1A and depicts the lower portion ofthe tool shown in FIG. 2.

Referring to the drawings in detail, reference character l@ generallyindicates a dual completion packing joint adapted to be interposedwithin an oil Well tubing string (not shown). The packing joint shownherein is particularly designed and constructed for utilization with twovertically spaced oil or gas bearing formations (not shown). However, itwill be apparent that the tool 10 may be lengthened and modied for usewith more than two vertically spaced fluid bearing formations, ifdesired.

The packer tool 1d comprises an inner mandrel l2 slidably ortelescopically disposed within an outer sleeve 14. The upper end i6 ofthe mandrel 12 is threaded to receive a suitable sub or tubular member13 for a purpose as will be hereinafter set forth. The sub member 1S isprovided with suitable threads Ztl at the upper end thereof for threadedconnection with the oil well tubing string (not shown) in any well knownmanner. An inwardly extending circumferential shoulder 22 is provided inthe tubular member 18 and spaced above the mandrel 12 to provide a seatfor a suitable nipple member (not shown) in order to seal the tubingstring from the flow of fluid when it is necessary to pull the tubingand the packer joint from the Well for any reason.

An upper stationary' packing sleeve 24 is provided between the innermandrel 12 and the outer sleeve 14. The packing sleeve 24 is preferablyconstructed from a suitable packing rubber or may be constructed fromsuitable steel packing material when the unit or tool 10 is utilizedunder high temperature conditions. The packing sleeve 24 rests on anupper shoulder 26 of an inwardly directed circumferential lug member 2Sprovided on the inner periphery of the outer sleeve 14. The upper end 30of the outer sleeve 14 is internally threaded to receive a retainingring 32. The ring 32 bears downwardly against the packing sleeve 24 forassuring an eillcient seal between the inner mandrel 12 and outer sleeve14, as will be hereinafter set forth. A suitable jamb nut 34 isthreadedly secured to the upper end 30 of the sleeve 14 for urging theretaining ring 32 downwardly into a tight engagement with the packingsleeve 24.

The mandrel 12 extends longitudinally through the j.:n1b nut 34 and isslidable therein. A suitable set screw 36, or the like, extendstransversely through the sidewall of the jamb nut 34 and intodisposition within a longitudinal groove 3S provided on the outerperiphery of the inner mandrel 12. In this manner, the mandrel 12 maymove longitudinally with respect to the nut 34. However, any rotationalmovement of the mandrel 12 is transmitted to the jamb nut 34 through theconnection between the female spline 38 and the set screw 36. The upperend of the groove 38 is closed at 3% in order to preclude any accidentaldisengagement of the groove and the screw 36.

The inner mandrel 12 is provided With a plurality of spaced apertures 40for a purpose as will be hereinafter set forth. An outwardly extendingcircumferential flange 42 is provided on the outer periphery of themandrel 12 and spaced below the apertures 40. The flange 42 is adaptedto contact the lower shoulder 44 of the flange 28 in order to limit theupward movement of the inner mandrel 12 with respect to the outer sleeve14. A suitable packing sleeve member 46 is provided around the mandrel12 below the flange 42 to preclude leakageof uid between the mandrel 12and the sleeve 14. The mandrel 12 is provided with an externallythreaded portion 48 at the lower end thereof for receiving a packingretainer ring 59. The retainer ring '50 is preferably threadedly securedon the mandrel 12 for urging the packing member 46 upwardly against theflange 42, thereby assuring an eicient seal between the mandrel 12 andthe sleeve 14.

The outer sleeve 14 is threaded at the lower end 52 thereof to receive alower sleeve member 54.. A lower mandrel member 56 is threadedly securedto the lower end 48 of the mandrel 12 and extends longitudinally throughthe lower sleeve 54. An outwardly extending circumferential llange 58similar to the flange 42 is provided on the outer periphery of the lowermandrel 56 for contacting an inwardly directed circumferential flange 60provided on the inner periphery of the lower sleeve 54. In this manner,the downward movement of the mandrel 12 and mandrel 56 connected theretois limited with respect to the outer sleeve 14 and lower sleeve 54. Thelower mandrel 56 is provided with a plurality of spaced apertures 62 anddisposed below the llange 53, for a purpose as will be hereinafter setforth. A transverse partition member 64 is suitably secured to the innerperiphery of the lower mandrel S6 by welding, or the like, and is spacedbelow the apertures 62. A plurality of spaced apertures 66 are providedin the lower mandrel 56 below the partition 64 for a'purpose as will behereinafter set forth.

A lower stationary packer sleeve 68 is provided in the lower sleeve 54around the lower mandrel 56 and is positioned below the flange 6i). Thelowermost end 70 of the lower sleeve 54 is internally threaded toreceive a retainer ring 72. The ring 72 is preferably disposed adjacentthe packing sleeve 68 for urging the packing sleeve upwardly against theflange 60. It will be apparent that the longitudinal compression of thepacking sleeve 63 between the ring 72 and flange 60 will cause a radialexpansion of the packing sleeve for assuring an eillcient sealingbetween the lower sleeve 54 and lower mandrel A suitable coupling memberor jamb nut 74 is threadedly secured in the lower end 70 of the sleeve54 and into abutment with the retainer ring 72 for securely retainingthe ring 72 in a tight engagement with the packing sleeve 68.

The jamb nut 74 is threaded at its lower end 76 for receiving anysuitable well tubing packer joint 78, such as is normally utilized foranchoring the well tubing securely within the well casing. There aremany types of these packer joints in use in the industry, and anysuitable packer joint may be utilized. A frangible disc member St) isthreadedly secured within the packer joint 78 in the proximity of thelower' end 76 of the jamb nut 74. A rod member 82 is welded, or thelike, to the transverse partition plate 64 and extends longitudinallydownward therefrom through the open lower end 84 of the lower mandrel56. A suitable centering spider member 86 is secured adjacent the openend 34 in any well known manner for maintaining the rod 82concentrically positioned within the lower mandrel 56. A downwardmovement of the rod 82 with respect to the jamb nut 74, as will behereinafter set forth, will force the rod 82 through the frangible discfor a fracturing thereof, thus opening the interior of the lower mandrel56 and mandrel 12 to the ilow of the well fluid.

Operation When it is desired to produce oil or oil and gas products frommore than one producing horizon or oil bearing formation (not shown) inone Well bore, a packer joint 14 is interposed in the well tubing insuch a manner that the joint 1t? will be disposed within the well casingin the proximity of the oil bearing formations. It will be apparent thatthe over-all length of the tool 10 may vary according to the verticalspacing of the oil bearing horizons.

A plurality of spaced apertures 88 are provided in the outer sleeve 114spaced below the flange 28 whereby the apertures 88 will be incommunication with the uppermost of the two oil bearing formations. Thewell tubing packer member 78 is expanded or set in any suitable manner(not shown) as is well known for securely anchoring the tubing stringand the tool joint 10 within the well casing. The packer member 78 ispreferably vertically disposed within the casing between the upper andlower oil bearing formations in order to provide a seal between the twoiluid producing zones. In this manner, the fluid of the upper oil zonewill be maintained separate and independent from the lower oil zone. Thelower end of the well tubing (not shown) is normally open for receivingthe tluid of the lower oil zone therein, as will be hereinafter setforth.

After the packer 78 has been set for securing the tubing and dualpacking joint 10 within the well casing, the weight at the surface ofthe well bore may be slacked off whereby the well tubing will tend tomove downwardly in the well casing. The outer sleeve 14 and lower sleeve54 are precluded from any downward movement by their direct connectionwith the anchoring packing member 78. Thus, the inner mandrel 12 andlower mandrel 56 will be moved downwardly through the outer sleeve 14and lower sleeve 54 by the weight of the tubing string thereabove. Thedownward movement of the inner and lower mandrels causes the rod 82 tomove downwardly through the frangible disc 8G whereby the disc will befractured. In this manner, communication is established between theinterior of the lower mandrel 56 and the open lower end of the welltubing, as hereinbefore set forth. The well tluid from the lower oilzone may thus low into the lower aca/geste mandrel 56. It will beapparent that the llow of the well uid may be induced in any suitablemanner, such as pumping or the like, in instances wherein the wellpressure is not suflicient for a natural ow of the oil.

The partition plate 64 limits the upward travel of the well fluid fromthe lower oil zone through the lower mandrel 56. Thus, the well uid willflow outwardly through the apertures 66. it will be apparent, however,that the apertures 66 are disposed adjacent the lower stationary packingsleeve 68 when the mandrel 56 is in its lowermost position, as shown inFIG. 2, thus the uid from the lower oil zone cannot low out of themandrel 56, and is contained therein as long as the mandrel 56 ismaintained in the lowermost position. As hereinbefore set forth, thedownward movement of the mandrel 56 is limited by the contact betweenthe flanges 58 and 60, thereby assuring that the apertures 66 will bedisposed adjacent the packing sleeve 68 in the lowermost positiontherefor. As shown in FIG. 2, the apertures 40 of the inner mandrel 12are positioned in the proximity of the apertures 88 provided in theouter sleeve 14 when the mandrel 12 is in its lowermost positiontherein. e well uid present in the upper oil zone is then free to owinto the sleeve 14 and into the interior of the inner mandrel 12. Theslidable packing member 46 precludes any downward ow of the well fluidaround the mandrel 12, and the upper stationary packing sleeve 24precludes any upward flow of the fluid around the mandrel 12. Thus, theuid in the upper oil zone will be directed into the interior of theinner mandrel 12. The partition 64 closes the lower portion of the innermandrel 12, and since the lower apertures 62 are positioned adjacent thelower stationary packing sleeve 68, the Huid from the upper oil zonewill accumulate within the mandrel 12 above the partition 64. Ashereinbefore set forth, the well Huid may be produced in any suitablemanner, such as by a natural ow or by pumping the Huid to the surface ofthe well bore.

As the well lluid from the upper oil zone moves upwardly within themandrel 12, it will move through the tubular member 18, and into thewell tubing string connected thereabove (not shown). Thus, the wellfluid from the upper oil zone may be produced through the well tubing,thereby precluding contact of the well iluid with the inner periphery ofthe well casing, and eliminating the possibility of any paraliinaccumulating thereon. The fluid from the upper oil zone may be producedthrough the well tubing in this manner as long as desired by maintainingthe mandrels 12 and 56 in their lowermost position with respect to theouter sleeve 14 and lower sleeve 54. The fluid from the lower zone willbe positively sealed off and cannot in any manner be mixed with thefluid from the upper zone.

When it is desired to stop the flow of fluid from the upper zone andbegin producing the fluid from the lower oil zone, the weight on thewell tubing may be picked up at the surface of the well in any wellknown manner (not shown) whereby the inner mandrel l2 and lower mandrel56 secured thereto will be raised vertically within the outer sleeve 1dand lower sleeve 54. As hereinbefore set forth, the upward movement ofthe mandrel 12 is limited by the contact between the flanges 28 and 4-2.With the mandrels 12 and 56 in their uppermost position, as shown inFIG. l, the apertures 4t) of the mandrel 12 are disposed adjacent theupper stationary packing sleeve 24. Simultaneously, the slidable packersleeve 46 is moved into a position adjacent the apertures 88 of theouter sleeve 14, thus shutting off communication between the upper oilzone and the interior of the mandrel i2. However, the apertures 62 and66 of the lower mandrel 56 are moved upwardly and out of contact withthe lower stationary packing sleeve 68. Thus, the well fluid of thelower oil zone which is contained within the lower mandrel S6 below thepartition 64 may ow outwardly through the apertures 66 and into theannular space 9-9 between the sleeve 54 and mandrel 56, as shown inFIG. 1. The lower packing sleeve 68 precludes any downward flow of theuid from the annular space 90, and the slidable packing sleeve 46precludes any upwardly ow of the fluid around the mandrels S6 and 12.The uid from the lower oil zone will thus flow into the interior of themandrel 56 above the partition 64 through the apertures 62 forcommunication with the interior of the mandrel 12, whereby it will owupwardly for production through the well tubing as hereinbefore setforth.

It will be apparent that the fluid from the lower oil zone may beproduced through the well tubing as long as desired by maintaining themandrels 12 and 56 in their uppermost position with respect to the outersleeve 14 and lower sleeve 54. The uid from the upper oil zone ispositively sealed off from the interior of the mandrel 12, and can in nomanner be intermingled accidentally with the fluid owing from the loweroil zone.

By way of summary, the present invention provides a simple and eliicientdual completion packing tool which may be easily installed within aproducing well in order to produce well fluid from a plurality ofvertically spaced subsurface oil bearing formations. The tool may bereadily positioned for production from only one of the oil producinghorizons by telescopically positioning the inner mandrel within theouter sleeve. An upper position for the inner mandrel providescommunication between the upper oil zone and the interior of the welltubing while simultaneously sealing off the uid from the lower oil zone.Conversely, a lowered position of the mandrel provides communicationbetween the lower oil zone and the interior of the well tubing whilesimultaneously sealing olf the ow of the tluid from the upper oil zone.

From the foregoing, it will be apparent that the present inventionprovides a novel dual completion packer joint which may be easilyinterposed Within the well tubing of a producing oil well for permittinga separate fluid production from multiple subsurface oil bearinghorizons. The novel tool may be utilized at substantially any depthwithin the well bore in accordance with the disposition of the oilbearing horizons. The positive action of the novel tool provides Ifor asimplicity of operation with an eicient control of the flow of the fluidfrom the subsurface formations. The novel tool is simple and efficientin operation and economical and durable in construction.

Changes may be made in the combination and arrangement of parts asheretofore set forth in the specification and shown in the drawings, itbeing understood that any modication in the precise embodiment of theinvention may be made within the scope of the following claims withoutdeparting from the spirit of the invention.

I claim:

l. A dual completion packer joint for an oil well having upper and loweroil bearing formations, and comprising an outer sleeve member adapted tobe anchored within the well bore, an inner mandrel telescopicallydisposed Within the outer sleeve, means providing communication betweenthe upper oil bearing formation and the interior of the mandrel, meansproviding communication between the lower oil bearing formation and theinterior of the mandrel, an imperforate member disposed within themandrel for precluding -a mixing of the fluids from the upper and lowerformations, said inner mandrel in one position having communication withthe upper oil bearing formation, a packing member carried `by the outersleeve for precluding `communication of the lower oil bearing formationwith the interior of the mandrel in the rst mentioned position for saidinner mandrel, said inne-r mandrel in a second position havingcommunication with the lower oil bearing formation, passageway meansprovided for bypassing the imperforate member in the said secondposition of the inner mandrel, and a second packing member carried bythe outer sleeve and cooperating with the inner mandrel for precludingcommunication of the upper oil bearing formation and the interior of themandrel in the second position for said inner mandrel, and a thirdpacking member carried by the mandrel and cooperating with said mandreland the outersleeve for precluding the comrningling of the upper andlower formation fluids.

2. A dual completion packer unit for an oil well having upper and lowerfluid bearing formations, and comprising an outer sleeve member, aninner mandrel telescopically disposed within the sleeve member, meansfor limiting the telescopic movement of the mandrel member with respectto the sleeve member, said mandrel provided with open upper and lowerends, a packing sleeve provided in the upper portion of the outer sleevemem-ber between the inner mandrel and outer sleeve member and stationarywith respect to the outer sleeve member, a slidable second packingsleeve member provided between the mandrel and outer sleeve member andslidable with respect to the outer sleeve member, a plurality ofapertures provided in the outer sleeve member below the upper packingsleeve and adjacent to the upper formation, a plurality of upperapertures provided in the inner mandrel, said mandrel in a firstposition relative to said outer sleeve providing communication betweensaid apertures and the open upper end of the mandrel, a member disposedwithin the mandrel for precluding communication between the open lowerend and the open upper end of the mandrel in the said -rst position ofthe mandrel, said mandrel in a second position relative to said outersleeve member providing communication between the open lower end andopen upper end thereof for permitting production from the lowerformation, passageway means provided for bypassing the member within themandrel when the mandrel is in the said second position, and theaforementioned packing sleeves precluding communication between theapertures in the outer sleeve and the open upper end of the mandrel insaid second position for said mandrel, and the second packing sleevecooperating with the outer sleeve and the inner mandrel for precludingcommingling of the upper and lower formation uids.

3. A dual completion packer tool for an oil well having upper and lowerfluid bearing formations, and comprising an outer sleeve, an innermandrel telescopically disposed within 'the sleeve, said inner mandrelprovided with a plurality of spaced upper and lower apertures, saidsleeve provided with a plurality of circumferentially spaced aperturesadjacent to the upper formation, lug means cooperating between themandrel and sleeve for limiting the telescopic movement of the mandrelwithin the sleeve, a lower stationary packing sleeve provided betweenthe mandrel and sleeve and stationary with respect to the sleeve forsealing the lower apertures of the mandrel in a lowered position thereofwithin the sleeve, said upper apertures of said mandrel positioned incommunication with the apertures of the sleeve in the lowered positionfor the mandrel for production from the upper formation, meanspreoluding communication between the open lower end and the open upperend of the mandrel in the lowered position of the mandrel, passagewaymeans for by-passing said last mention-ed means in the raised positionof the mandrel, packing means provided between the mandrel and sleeveand Vstationary with respect to the sleeve for sealing the upperapertures and sleeve apertures in a raised position for the mandrelwithin the sleeve, said lower apertures open for receiving fluid fromthe lower formation in the raised position for the mandrel.

4. A dual completion packer tool for an oil well bore containing upperand lower iiuid bearing formations, and

comprising an outer sleeve member adapted to be anchored within the wellbore, an inner mandrel telescopically disposed within the outer sleevemember, said outer sleeve member provided with a plurality of spacedapertures in communication with the -well uid of the upper formation,said inner mandrel provided with a plurality of spaced upper and lowerapertures, cooperatingy fiange members for limiting the upward anddownward movement of the inner mandrel, a packing sleeve member carriedby the outer sleeve for sealing the lower apertures from the well fluidduring a lowered position of the inner mandrel within the outer sleeve,said upper apertures disposed in communication with the apertures of theouter sleeve in a lowered position for the inner mandrel whereby thewell fluid of the upper formation is directed into the inner mandrel, animperforate member disposed within the mandrel and precluding thedownward ow of the well lluid in the inner mandrel, a second packingsleeve member carried by the outer sleeve for sealing the upperapertures and the outer sleeve apertures in a raised position of theinner mandrel, said lower apertures opened to receive Well iiuid fromthe lower formation in said raised position of the inner mandrel wherebythe well Huid is directed into the inner mandrel above said imperforatemember, and a-third packing sleeve slidably carried within the outersleeve by the mandrel and cooperating therebetween to precludecommingling of the upper and lower formation fluids.

5. A dual completion packer tool for an oil well bore containing upperand lower uid bearing formations, and comprising an outer sleeve memberadapted to be anchored within the well bore, an inner mandreltelescopically disposed within the outer sleeve member, said outersleeve member provided with a plurality of spaced apertures incommunication with the well uid of the upper formation, said innermandrel provided with a plurality of spaced upper and lower apertures,means cooperating between the outer sleeve and inner mandrel for|limiting the upward and downward movement of the inner mandrel, apacking sleeve member carried by the outer sleeve for sealing the lowerapertures from the well fiuid during a lowered position of the innermandrel within the outer sleeve, said upper apertures disposed incornmunica'tion with ythe apertures of the outer sleeve in a loweredposition for the inner mandrel whereby the well uid of the upperformation is directed into the inner mandrel, an imperforate membersecured within the mandrel for preoluding the downward flow of the wellfluid in the inner mandrel, a second packing sleeve member carried bythe outer sleeve for sealing the upper apertures and the outer sleeveapertures in a raised position of the inner mandrel, said lowerapertures opened to receive well fluid from the lower formation in araised position of the inner mandrel whereby the well fluid is directedinto the inner mandrel and the imperforate member is bypassed, and athird packing sleeve carried by the inner mandrel and cooperating withthe outer sleeve to preclude commingling of the upper and lowerformation uids.

References Cited in the iile of this patent UNITED STATES PATENTS1,901,813 Johnston Mar. 14, 1933 2,327,610 Savitz Aug. 24, 19432,403,987 Lewis July 16, 1946 2,690,807 Moosman Oct. 5, 1954 2,720,926Brown Oct. 18, 1955 2,951,536 Garrett Sept. 6, 1960

